Continuing the epic science fiction series that began with 2010’s Pathfinder, this overstuffed but fascinating second installment sees trapper-turned-royal-exile Rigg and his companions exploring more of their compartmentalized world, while mastering their various time travel–related abilities and negotiating complicated interpersonal relationships. The brilliant yet complicated premise, which sees the young quintet racing to save the world while unable to fully trust anyone they meet or anything they learn, is weighed down somewhat by roundabout conversations and overly angsty internal monologues in which characters simmer over perceived slights or insecurities. However, the way Card explores time travel, logic puzzles, and parallel societal development, as well as the clever fashion in which various problems are resolved and the engrossing details of the world he has created, keep the plot moving forward—and often backward in time. For all its twisty, intelligent, and thought-provoking intricacy, the story still seems best summed up by the observation of one character: “I really hate philosophy.... You talk and talk, and in the end, you don’t know any more than you did.” Ages 12–up. Agent: Barbara Bova Literary Agency. (Oct.)